1. Field of the Invention
The invention relates to a method and a device for producing back-foamed air-permeable textile products such as back-foamed mats as a floor covering for motor vehicles, seat upholstery, head rests and the like, and to a back-foamed air-permeable textile product of this type.
2. Related Technology
The above-mentioned products are typical representatives of such air-permeable textile products which can be back-foamed on the back turned away from a useful or visible face.
In the case of floor coverings for a motor vehicle, the back-foamed mat has the function not only of compensating for unevenness in a vehicle floor relative to the desired planar configuration in the vehicle interior but also of receiving cables and of insulating and damping undesirable noises. The mat is an air-permeable textile product, generally a carpet web, which is tufted in a textile air-permeable carpet substrate.
In the case of seat upholstery, head rests and the like, back-foaming of the textile product, generally a fabric, in turn has the function of giving the seat upholstery or the head rest a desired form which improves the sitting posture. Acoustic effects here are relatively insignificant, it being more important additionally to achieve very good climatic comfort. Climatic comfort refers to the property whereby air can circulate through the textile product, even when it is back-foamed, so that atmospheric moisture can be transported and air can also circulate easily, leading to rapid compensation in terms of ambient temperature and ambient humidity, in particular also when a person is using the seat upholstery or the head rest.
Conventionally the air-permeable textile product, for example a mat blank, etc., is inserted into a mould with the useful or visible face resting on one mould half for typical manufacture. The mold is then closed and the reaction product is introduced to form the back-foaming foam such as polyurethane foam. A relatively high pressure is produced during the reaction of the reaction products. Since the textile product is air-permeable, usually being a hosiery or knitted fabric or the like with high porosity, and due to the action of capillary forces, at least one of the reaction products, possibly all of them, can pass through these pores or openings in the fabric to the visible face of the textile product, where they adhere to any parts provided there. Any foam which is being formed can also pass through these pores. This is highly undesirable. Back-foamed textile products in which the visible face has adhesive regions or in which the foam has passed to the visible face cannot be sold.
To overcome this problem, a film is provided on the back of the mat as an acoustically effective component (DE 38 09 980 C2) with a known method for manufacturing floor coverings. Closed-cell thin foam layers have also been proposed. The known provision of a film is counter-productive to the achievement of climatic comfort as it prevents the circulation of air. A film of this type, which is impermeable to air, is also undesirable with respect to the acoustic properties.
It is known from DE 691 13 137 T2 to destroy such a film, at least in part, after manufacture of the back-foamed product by additional methods, the effect of heat combined with the production of a reduced pressure. The additional process steps required here are obviously very expensive and complex, and the complete or uniform removal or perforation of the film cannot be reproducibly ensured. Residues of the film adversely affect the flow resistance at the respective positions. Therefore, this procedure is not particularly suitable, especially for mass production.